Method of making thin film devices

ABSTRACT

A thin film device includes a substantially flat ceramic substrate having bevelled surfaces formed in opposite corners of a major flat surface at one end thereof. Tantalum nitride is sputtered simultaneously onto the major flat surface and the bevelled surfaces to form a resistive film thereon. Thereafter a contact material is directed, in an evaporation process, onto an end edge surface of the ceramic substrate which is adjacent to the bevelled surfaces. The contact material is thereby deposited simultaneously onto the end edge surface and the bevelled surfaces having portions of the tantalum nitride film thereon. The contact material which was deposited onto the end edge surface of the substrate is removed so that the contact material remains only on the bevelled surface in overlapping engagement with underlying portions of the tantalum nitride film. This provides thin film device having contact areas in electrical connection with the tantalum nitride film to provide connection of the film with external circuits.

United States Patent [191 Hudnall METHOD OF MAKING THIN FILM DEVICES [75] Inventor: Joseph R. Hudnall, Lancaster, Ohio [73] Assignee: Western Electric Company,

Incorporated, New York, N .Y.

[22] Filed: Nov. 6, 1970 [21] Appl. No.: 87,462

117/227, 106 R, 106 A, 107; 29/619, 621, 625, 620, 628, 630 R; 338/252 [5 6] References Cited UNITED STATES PATENTS 3,437,888 4/1969 Hall 117/212 X 3,469,226 9/1969 Solow 338/252 3,329,922 7/1967 Steil 29/621 X 3,345,210 10/1967 Wilson 117/212 3,161,457 12/1964 Schroeder et al. 117/212 X 3,591,413 7/1971 Seki et a1. 117/227 X 3,387,952 6/1968 Chapelle 117/227 X 3,322,655 5/1967 Garibotti et al. 117/43 X 2,563,936 8/1951 Huntsberger 117/43 X 2,000,226 5/1935 Fry 117/43 X 2,063,268 12/1936 Plunkett 117/43 X Oct. 16, 1973 FOREIGN PATENTS OR APPLICATIONS 932,210 7/1963 Great Britain Primary Examiner-Ralph S. Kendall Att0rneyW. M. Kain, R. P. Miller and Don P. Bush [5 7] ABSTRACT A thin film device includes a substantially flat ceramic substrate having bevelled surfaces formed in opposite corners of a major flat surface at one end thereof. Tantalum nitride is sputtered simultaneously onto the major flat surface and the bevelled surfaces to form a resistive film thereon. Thereafter a contact material is directed, in an evaporation process, onto an end edge surface of the ceramic substrate which is adjacent to the bevelled surfaces. The contact material is thereby deposited simultaneously onto the end edge surface and the bevelled surfaces having portions of the tantalum nitride film thereon. The contact material which was deposited onto the end edge surface of the substrate is removed so that the contact material remains only on the bevelled surface in overlapping engagement with underlying portions of the tantalum nitride film. This provides thin film device having contact areas in electrical connection with the tantalum nitride film to provide connection of the film with external circuits.

9 Claims, 9 Drawing Figures PATENTED URI 16 I975 SHEET 10F 2 lNVENTOR J R HUDNALL A T TORNE V METHOD OF MAKING THIN FILM DEVICES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to thin film devices and methods of making the devices, and particularly relates to thin film devices having contact areas and methods of making the devices without the need for masking and etching techniques.

2. Description of the Prior Art Thin film devices are manufactured by using various techniques, such as sputtering, evaporation, electrodeposition and the like. Generally, such techniques require masking and etching to form an ultimate product. For example, in the manufacture of thin film resisotrs using tantalum nitride as the resistive material, the tantalum nitride is sputtered as a film onto a major flat surface of a ceramic substrate. In order to provide electrical connection with the film, multiple layers of different contact materials must then be placed over selected spaced portions of the tantalum nitride film. Generally, the different contact materials can be placed on the tantalum nitride film in several different ways. For example, the different contact materials can be evaporated onto the entire exposed surface of the tantalum nitride and then, through a masking and etching technique, the unwanted portions of the contact materials are removed so that only those areas of contact material remain which are necessary to facilitate external connection of the resistive film with other circuits.

Another method of placing the different contact materials on the desired areas on the tantalum nitride film involves the masking of portions of the tantalum nitride film to cover those areas which are not to be ultimately covered by the different contact materials, and thereafter evaporating the contact materials onto the exposed areas of the tantalum nitride film. Since the mask is adjacent to the exposed areas of the tantalum nitride film, some of the contact materials will deposit on the mask. In a process such as this, the different contact materials which are deposited on the mask must be removed. In addition, the masking step must be utilized just as it is utilized in the process where the unwanted contact material is etched away.

While these examples refer to thin film resistors, other types of thin film devices require contact material to be placed in selected areas to facilitate connections with external circuits. The method of placing the various types of thin film circuits onto the substrate are well known and need not be explained here. However, techniques for placing the contact material in the desired locations on the thin film device utilize procedures similar to those explained hereinabove with respect to the tantalum nitride resistor.

The unused portions of the different contact materials in the explained examples should be recovered. However, because the different materials are placed in layers, the materials to be recovered are contaminated thereby requiring costly reclaiming processes.

Hence it becomes obvious that there is a need for new and improved techniques for manufacturing thin film devices in such a manner that the steps of placing contact material onto the devices are reduced and the material utilized during the process is also reduced.

Summary of the Invention It is, therefore, an object of this invention to provide new and improved thin film devices and methods of making the devices.

Another object of this invention is to provide new and improved thin film devices having structure which facilitates new and improved methods of making the devices to reduce the number of steps required and the amount of contact material utilized.

Still another object of this invention is the provision of new and improved thin film devices having contact areas which lie in a plane which intersects the plane supporting a circuit on the devices to facilitate new and improved methods of manufacturing the devices with relatively fewer steps and less contact material than previously required.

A thin film device illustrating certain principles of the invention may include a substrate having contiguous, multiple material-receiving surfaces which lie in at least two different planes which intersect at an acute angle where the surfaces diverge with a circuit-element film being supported on at least portions of the surfaces of the two different planes and conducting-material film overlapping portions of the circuit-element film in portions of at least one surface in one of the planes.

A method illustrating certain principles of the invention may include the steps of depositing simultaneously circuit-element film onto exposed areas of a substrate, which includes contiguous surfaces lying in at least two planes which intersect at an acute angle where the surfaces diverge, and thereafter depositing a contact material onto portions of at least one surface lying in one of the planes to provide connecting facilities between the circuit-element film and external circuits.

Brief Description of the Drawings Other objects and advantages of the present invention will be apparent from the following detailed description when considered in conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a substrate showing bevelled surfaces contiguous with a major flat surface of the substrate;

FIG. 2 is a perspective view showing the depositing of a film of a resistive material onto the flat and bevelled surfaces of the substrate illustrated in FIG. 1;

FIG. 3 is a perspective view showing a film of the deposited resistive material on the flat surface and the bevelled surfaces of the substrate illustrated in FIG. 1;

FIG. 4 is a perspective view showing the depositing of a film of a contact material onto the area of one end of the substrate which includes the bevelled surfaces illustrated in FIG. ll;

FIG. 5 is a perspective view showing a film of the contact material on the one end of the substrate and also in overlapping engagement with the resistive film on the bevelled surfaces of the substrate;

FIG. 6 is a perspective view showing a completed thin film device in accordance with certain principles of the invention;

FIG. 7 is a perspective view showing a stack of the substrates subsequent to the depositing of the resistive film thereon wherein contact material is being deposited thereon in accordance with certain principles of the invention;

FIG. 8 is a perspective view showing the stacked substrates with a film of the contact material deposited on the end and the bevelled surfaces thereof, and

FIG. 9 is a perspective view of the stacked substrates with the contact material removed from the ends of the substrates.

Detailed Description In manufacturing thin film devices, a plurality of steps involving masking and etching are required. In addition, considerable amounts of different contact materials, which are contaminated in the manufacturing procedures, are taken off in etching solution, and must be processed for recovery in costly operations. Therefore, it would be desirable to have a process which would substantially eliminate the masking steps required in the above techniques, reduce the amount of contact materials required, as well as reduce or minimize the effects of a costly operation to recover unused contact materials.

Subsequent to the manufacture of the thin film device, such as the tantalum nitride resistor, the resistive film is altered in some way, such as by anodizing or selective removal, to establish a precise and desired resistance value of the thin film resistor. Thereafter, terminating means are attached to the contact areas to facilitate connection to external circuits. It is noted that the attachment of the terminating means could be accomplished prior to the resistance value adjustment procedure. If the device is a thin film device of the type which includes various passive and active electrical elements, the terminating means must still be attached to the contact areas which are deposited in engagement with portions of the circuit-displayed on the device to facilitate connection of the thin film circuits with external circuits.

Referring now to FIG. 1, there is illustrated a ceramic substrate, designated generally by the numeral 16, which includes at least one major flat surface 17 and bevelled surfaces 18 and 19 formed in the major flat surface at one end thereof along an end edge surface 21. The forming of the bevelled surfaces 18 and 19 in the substrate 16 is accomplished in such away that the bevelled surfaces are contiguous with the major flat surface 17 and the end edge surface 21. Through-hole openings 22 and 23 are formed in the bevelled surfaces 18 and 19, respectively.

The substrate 16 is formed in such a manner that the major flat surface 17 lies in a first plane while the bevelled surfaces 18 and 19 lie in a second plane which intersects the first plane, with the intersecting planes forming an acute angle where the bevelled surfaces diverge from the, major flat surface. The end edge surface 21 lies in a third plane which intersects both the first and second planes. The intersection of the second and third planes forms an acute angle where the bevelled surfaces 18 and 19 diverge from the end edge surface 21. I

It is noted that the bevelled surfaces 18 and 19 could lie in two different planes, each of which intersect the first and third planes of the fiat surface 17 and the edge surface 21, respectively, and which would fall within the above definition of the second plane without departing from the spirit and scope of the invention.

Referring now to FIG. 2, the substrate 16 is positioned in such a manner that tantalum nitride is sputtered by a conventional process onto the major flat surface-17 and the bevelled surfaces 18 and 19. As illustrated in FIG. 3, as a result of the sputtering operation, a tantalum nitride resistive film 24 is deposited onto the major flat surface 17 (FIG. 1) of'the substrate 16 with portions 26 and 27 of the tantalum nitride film being deposited onto the bevelled surfaces 18 and 19. It is noted that the tantalum nitride film 24 and the portions 26 and 27 are joined togther to form an integral tantalum nitride resistive film. It is further obvious from FIGS. 2 and 3 that the positioning of the substrate 16, as illustrated in FIG. 2, permits the simultaneous sputtering of the tantalum nitride onto the major flat surface 17 and the bevelled surfaces 18 and 19, which lie in separate intersecting planes.

Referring now to FIG. 4, the substrate 16 is positioned so that a contact material can be evaporated onto the end edge surface 21 of the substrate and also onto the portions 26 and 27 of the tantalum nitride film 24 which are deposited on the bevelled surfaces 18 and 19 (FIGS. 1 and 2). As illustrated in FIG. 5, the evaporation process results in a contact material film 28 being deposited onto the end edge surface 21 (FIGS. 1 through 4) with portions 29 and 31 of the film being deposited in overlapping engagement with the underlying tively, of the film 24. The next film layer could be composed of a contact material such as titanium which provides adherence between the first and third film layers. The third film layer could be a contact material such as gold, copper or other suitable materials. The second and third film layers would be applied to the substrate in the same manner as that described with respect to FIGS. 4 and 5.

Referring now to FIG. 6, there is illustrated a completed thin film device, such as a thin film resistor, designated generally by the numeral 32. The portion of the contact material film 28, which is deposited onto the end edge surface 21, is removed by conventional techniques, such as abrading. The removal of the contact material from the end edge surface 21 leaves the portions 29 and 31 of the contact material in overlapping engagement with the underlying portions 26 and 27 (FIG. 3) of the tantalum nitride film 24. Since the openings 22 and 23 remain in the bevelled surfaces 18 and 19, respectively, terminating means, such as terminal pins (not shown) can be secured with or attached to the portions 29 and 31 of the contact material to provide connection between the tantalum nitride film 24 and external circuits.

The resistance value of the thin film resistor 32 can be adjusted by known techniques, .suchas-anodization or selective film removal.

Referring again to FIG. 4, the end edge surface 21 of the substrate 16 could be masked to prevent the depositing of the contact material onto the surface so that only the portions 29 and 31 (FIGS. 5 and 6) would be deposited onto the portions 26 and 27 (FIG. 3) of the tantalum nitride film 24. In this manner, when the mask is removed from the end edge surface 21 of the substrate 16, the thin film resistor 32, as illustrated in FIG. 6, would be completed.

Referring again to FIG. 1, the portion of the major flat surface 17, which extends between the bevelled surfaces 18 and 19, could be formed in such a manner that the entire end of the major flat surface was bevelled in the plane which includes the bevelled surfaces 18 and 19. During the evaporating process, wherein the contact material is deposited onto the portions 26 and 27 (FIG. 4) of the film 24, a masking technique could be utilized to shield those areas which should not be covered with the contact material. Further the bevelled surfaces 18 and 19 do not have to lie in the same plane in order to accomplish the method of making the thin film resistor 32, but the surfaces should at least lie in a plane other than the plane which includes the major flat surface 17 but in a plane which will facilitate the evaporation process, as illustrated in FIG. 4.

By utilizing the substrate 16 formed in the manner illustrated in FIG. 1, conventional masking and etching techniques, normally required in the manufacture of a thin film device, such as the thin film resistor 32, can be eliminated. This permits cost savings in material required to manufacture the thin film resistor 32, as well as in the time-consuming steps required to manufacture the resistor. As previously noted, other types of thin film devices, which include passive as well as active electrical elements, can utilize a substrate similar to the substrate 16 and gain the same advantages.

Referring now to FIG. 7, there is illustrated a stack of substrates 16-16, each of which have passed individually through the sputtering operation and include the tantalum nitride film 24, and the portions 26 and 27 thereof, as illustrated in FIG. 3. The substrates 16-16 are stacked in such a manner that each pair of substrates is stacked with the tantalum nitride film 24 being in interfacing engagement with the tantalum nitride film of the adjacent substrate of the pair, with the end edge surfaces 21-21 of the substrates appearing at a common end of the stack. Thereafter the contact material is deposited onto the end edge sudfaces 21-21 of the substrates 16-16 and the portions 26-26 and 27-27 of the film 24 of each substrate to simultaneously place the portions 29-29 and 31-31 of the contact material onto the individual substrates 16-16 in a manner similar to that illustrated in FIG. 5.

Referring now to FIG. 8, films 28-28 ofthe contact material cover the end edge surfaces 21-21 (FIG. 7) of the stack of substrates 16-16. In addition, the portions 29-29 and 31-31 of the contact material cover the underlying portions 26 and 27 (FIG. 3), respectively, of the film 24 of each of the substrates 16-16.

Referring now to FIG. 9, there is illustrated the stack of substrates 16-16 which have had the contact material removed from the end edge surfaces 21-21 to form a plurality of completed thin film resistors 32-32. The contact material which is evaporated onto the end edge surfaces 21-21, as shown in FIG. 8, is removed by any suitable means such as, for example, abrading. However, a mask could be used to cover the end edge surfaces 21-21 during the evaporating process so that there would not be any contact material evaporated onto the end edge surfaces. In this manner, only the film portions 26 and 27 of each substrate would have contact material evaporated thereon.

It is noted that multiple layers of different contact materials may be required to provide a satisfactory contact area for the thin film resistor 32. Application of the multiple layers of different contact materials may be accomplished by repeating, for example, the process explained with reference to FIGS. 7, 8 and 9.

Thus, the structure of the substrate 16 permits the cf- 5 ficient and economical manufacture of thin film devices, such as resistors 32, when made singly as well as when made in groups.

What is claimed is: 1. A method of making a thin film device having a substrate with a major flat surface and at least one bevelled surface formed inthe major flat surface, which comprises the steps of:

positioning the substrate to expose commonly and only the major flat surface and the at least one bevelled surface so that only the major flat surface and the bevelled surface of the substrate are exposed toward a direction from which circuit-element material can be directed for application thereto;

depositing simultaneously circuit-element material onto at least portions of the commonly exposed major flat surface and the bevelled surface to form a circuit-element film thereon;

positioning the substrate to expose only the bevelled surface toward a direction from which contact material can be directed for application thereto, and

depositing contact material onto at least spaced portions of the circuit-element film on the bevelled surface thereby forming a contact-material film to provide connecting facilities between the circuitelement film and external circuits.

2. A method of making at least two thin film devices wherein each device includes a substrate having a major flat surface and a bevelled surface formed in the 35 major flat surface, which comprises the steps of:

depositing circuit-element material onto the major flat surface and the bevelled surface of each of at least two substrates to form circuit-element films thereon;

assembling the two substrates together in a stack with the circuit-element films on the major flat surfaces of the two substrates being in interfacing engagement and the bevelled surfaces of the stacked substrates appearing at a common end of the stack of substrates, and

depositing contact-material simultaneously onto the circuit-element film on the bevelled surfaces appearing at the common end of the stack of substrates so that a contact-material film is formed thereon.

3. The method of making at least two thin film devices as set forth in claim 2, which further comprises the step of masking the end of the substrates whereat the bevelled surfaces appear prior to the depositing of contact-material material onto the circuit-element film on the bevelled surfaces so that the contact-material film is formed only onto the circuit-element film previously deposited onto the bevelled surfaces.

4. A method of making a thin film device having a substrate with a major flat surface and at least two, spaced, bevelled surfaces formed in and diverging from the major flat surface along a common edge of the substrate, which comprises the steps of:

positioning the substrate to expose commonly and only the major flat surface and the two, spaced, bevelled surfaces toward a direction from which circuit-element material is to be directed,

depositing simultaneously circuit-element material onto the major flat surface and the bevelled surfaces to form a integral circuit-element film,

positioning the substrate after forming the circuitelement film thereon to expose the bevelled surfaces toward a direction from which contact material is to be directed and to expose the major flat surface toward a direction other than the direction from which the contact mateial will be directed, and

depositing contact material simultaneously onto the circuit-element film on the two bevelled surfaces to form a contact-material film thereby providing connecting facilities between the circuit-element film and external circuits.

5. The method of making a thin film device as set forth in claim 4, which further comprises the steps of:

depositing contact material onto the common edge of the substrate simultaneously with the depositing of the contact material onto the circuit-element film on the bevelled surfaces, and

selectively removing the contact material from the common edge so that the only contact material remains on the circuit-element film on the bevelled surfaces.

6. A method of making at least two thin film devices wherein each device includes a substrate having a major flat surface and at least two, spaced, bevelled surfaces formed in and diverging from the major flat surface along a common edge of the substrate, which comrises the steps of:

depositing circuit-element material onto the major flat surface and the bevelled surfaces of each of at least two substrates to form circuit-element films thereon; I

assembling the two substrates together in a stack with the circuit-element films on the major flat surfaces of the two substrates being in interfacing engagement and the common edge of each substrate being substantially aligned so that the bevelled surfaces of the two substrates appear at'a common side of the stack of substrates, and

depositing contact-material simultaneously onto the circuit-element film on the bevelled surfaces appearing at the common side of the stack of substrates so that a contact-material film is formed thereon.

7. The method of making at least two thin film devices as set forth in claim 6, which further comprises the step of positioning the stack of substrates prior to the step of depositing the contact-material to expose only the common side of the stack and the circuitelement film on the bevelled surfaces toward a direction from which contact material is to be directed.

8. The method of making at least two thin film devices as set forth in claim 6, which further comprises the step of masking thecommon side of the stack of substrates so that only the circuit-element film on the bevelled surfaces is exposed to the depositing of the contact-material thereon. i

9. The method of making at least two thin film de-. vices as set forth in claim 6, which further comprises the steps of;

depositing contact-material onto the common side of the stack of substrates simultaneously with the depositing of the contact-material onto the circuitelement film on the bevelled surfaces of the two substrates, and I removing selectively the contact-material film on the common side of the stack of substrates so that contact-material film remains only on the circuitelement film on the bevelled surfces of the stacked substrates.

L- 566-PT UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3,765,937 Dated October 16, 1973 lnventor(s) J. R. Hudnall It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

./ mstract, line 15, "surface" should read --surfaces--. Abstract, line 17, after "provides" insert --a--. Column 1, line 5, delete "thin film devices and". Column 1, line 6, after "making" delete "the" and insert in place thereof --thin film--. Column 1 line 7, delete "thin film devices having contact areas and Column 1, line 8, delete "the devices" and insert in place thereof --thin film devices having contact areas-, Column 1, line 15, "resisotrs" should read "resistors"; Column 2, line 1, delete "thin film devices and". Column 2, line 2, after "making" delete "the" and insert in place thereof --thin-v-. Column 2, lines 3-5,

, delete "new and improved thin film devices having structure which facilitates". Column 2, lines 5-6, delete "the devices" and insert in place thereof --thin film devices in order". Column 2, lines 8-23, delete in their entirety. Column 7, line 9, "mateial" should read --materi al--. Column 7, line 31, "comrises should read --comprises--. Column 8, line 35, '"surfces" should read "surfaces".

Signed and sealed this 23rd day of April 19%..

Attest:

EDWARD I-LFLETGHER,JR. C. MARSHALL DANE Attesting Officer: Commissioner of Patents UNITED STATES PATENT OFFICE @ERTIFICATE OF CORRETION PatemNm 3,765,937 Dated October 16, 1973 lnventor(s) J. R. Hudnall It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

' fidastract, line 15, "surface" should read -surfaces--. Abstract] line 17, after "provides" insert --a-. Column 1, line 5, delete "thin film devices and"o Column 1, line 6, after "making" delete "the" and insert in place thereof --thin film--. Column 1 line 7, delete "thin film devices having contact areas and Column 1, line 8, delete "the devices" and insert in place thereof -thin film devices having contact areas Column 1, line 15, "resisotrs" should read "resistors"; Column 2, line 1," delete "thin film devices "and". Column 2, line 2, after "making" delete "the" and insert in place thereof -thin- Column 2, lines 3-5, delete "new and improved thin film devices having structure which facilitates". Column 2, lines 5-6, delete "the devices" and insert in place thereof --thin film devices in order-o Column 2, lines 8-23, delete in their entirety. Column 7, line 9 "mateial" should read --materi al--. Column 7, line 31, "comrises should read -comprises-. Column 8, line 35, "'surfces" should read "surfaces-n Signed sealed this 23rd day of April 1974.

( SEAL Attest:

EDWARD ILFLETCHEELJR. C I IARSHALL DAM? Attesting Officer Commissioner of Patents 

2. A method of making at least two thin film devices wherein each device includes a substrate having a major flat surface and a bevelled surface formed in the major flat surface, which comprises the steps of: depositing circuit-element material onto the major flat surface and the bevelled surface of each of at least two substrates to form circuit-element films thereon; assembling the two substrates together in a stack with the circuit-element films on the major flat surfaces of the two substrates being in interfacing engagement and the bevelled surfaces of the stacked substrates appearing at a common end of the stack of substrates, and depositing contact-material simultaneously onto the circuit-element film on the bevelled surfaces appearing at the common end of the stack of substrates so that a contact-material film is formed thereon.
 3. The method of making at least two thin film devices as set forth in claim 2, which further comprises the step of masking the end of the substrates whereat the bevelled surfaces appear prior to the depositing of contact-material material onto the circuit-element film on the bevelled surfaces so that the contact-material film is formed only onto the circuit-element film previously deposited onto the bevelled surfaces.
 4. A method of making a thin film device having a substrate with a major flat surface and at least two, spaced, bevelled surfaces formed in and diverging from the major flat surface along a common edge of the substrate, which comprises the steps of: positioning the substrate to expose commonly and only the major flat surface and the two, spaced, bevelled surfaces toward a direction from which circuit-element material is to be directed, depositing simultaneously circuit-element material onto the major flat surface and the bevelled surfaces to form a integral circuit-element film, positioning the substrate after forming the circuit-element film thereon to expose the bevelled surfaces toward a direction from which contact material is to be directed and to expose the major flat surface toward a direction other than the direction from which the contact material will be directed, and depositing contact material simultaneously onto the circuit-element film on the two bevelled surfaces to form a contact-material film thereby providing connecting facilities between the circuit-element film and external circuits.
 5. The method of making a thin film device as set forth in claim 4, which further comprises the steps of: depositing contact material onto the common edge of the substrate simultaneously with the depositing of the contact material onto the circuit-element film on the bevelled surfaces, and selectively removing the contact material from the common edge so that the only contact material remains on the circuit-element film on the bevelled surfaces.
 6. A method of making at least two thin film devices wherein each device includes a substrate having a major flat surface and at least two, spaced, bevelled surfaces formed in and diverging from the major flat surface along a common edge of the substrate, which comprises the steps of: depositing circuit-element material onto the major flat surface and the bevelled surfaces of each of at least two substrates to form circuit-element films thereon; assembling the two substrates together in a stack with the circuit-element films on the major flat surfaces of the two substrates being in interfacing engAgement and the common edge of each substrate being substantially aligned so that the bevelled surfaces of the two substrates appear at a common side of the stack of substrates, and depositing contact-material simultaneously onto the circuit-element film on the bevelled surfaces appearing at the common side of the stack of substrates so that a contact-material film is formed thereon.
 7. The method of making at least two thin film devices as set forth in claim 6, which further comprises the step of positioning the stack of substrates prior to the step of depositing the contact-material to expose only the common side of the stack and the circuit-element film on the bevelled surfaces toward a direction from which contact material is to be directed.
 8. The method of making at least two thin film devices as set forth in claim 6, which further comprises the step of masking the common side of the stack of substrates so that only the circuit-element film on the bevelled surfaces is exposed to the depositing of the contact-material thereon.
 9. The method of making at least two thin film devices as set forth in claim 6, which further comprises the steps of: depositing contact-material onto the common side of the stack of substrates simultaneously with the depositing of the contact-material onto the circuit-element film on the bevelled surfaces of the two substrates, and removing selectively the contact-material film on the common side of the stack of substrates so that contact-material film remains only on the circuit-element film on the bevelled surfaces of the stacked substrates. 